Sealing rail with heat pipe for a packaging machine

ABSTRACT

The present invention relates to a sealing rail for a packaging machine. The sealing rail has least one heating unit that is provided in a heating bar, and a sealing surface that is provided on a sealing bar. The sealing rail has at least one heat pipe that is oriented parallel to the sealing surface and in contact with both the heating bar and the sealing bar so as to transfer heat homogeneously from the heating bar to the sealing bar.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to European Patent Application Number 13198914.7 filed Dec. 20, 2013, to Konrad Möβnang, currently pending, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a sealing rail for a packaging machine.

BACKGROUND OF THE INVENTION

EP 1 403 185 A1 discloses a vacuum chamber machine comprising a sealing rail that is continuously heated by means of a resistance heating unit. A resistance heating unit may consist of tubular heaters or heating cartridges. The drawback of tubular heaters is that they have an inhomogeneous temperature profile along their orientation so that a sealing rail of one meter in length, for example, may exhibit differences in temperature of up to 15° C. on its sealing surface. When such a vacuum chamber machine is used for packaging medical products, the admissible differences in temperature are in some cases only a few degrees centigrade so as to guarantee reliable sealing along the entire length of a sealed seam.

Tubular heating elements, especially in the form of a heat pipe, have been known for a long time, as shown in U.S. Pat. No. 2,350,348, and are used in notebooks for the purpose of cooling microprocessors. A heat pipe is a heat transfer device which, by making use of the evaporation heat of a working fluid, allows a high thermal flow density so that large quantities of heat can be conveyed on the basis of a comparatively small cross-sectional area. Heat pipes always comprise a hermetically sealed volume, normally in the form of a pipe. This pipe is filled with a working fluid that fills the volume, part of it in a liquid and part of it in a vaporous condition.

SUMMARY OF THE INVENTION

It is the object of the present invention to improve a sealing rail for a vacuum chamber machine such that the sealing surface exhibits the smallest possible temperature differences along the sealing rail.

The sealing rail according to one embodiment of the present invention comprises at least one heating unit, which may be provided in a heating bar, and a sealing surface, which may be provided on a sealing bar. The sealing rail can be characterized in that at least one heat pipe is provided that may be oriented parallel to the sealing surface and may be in contact with both the heating bar and the sealing bar so as to transfer the heat homogeneously from the heating bar to the sealing bar. Within the meaning of the present invention, the formulation “homogenous” means that heat which is largely uniform along the heat pipe is transferred to the sealing bar so that there are hardly any differences in temperature. This entails the enormous advantage that it is possible to guarantee differences in temperature on the sealing surface which are so small that the highest demands on sealing quality, especially in the field of medicine, can be satisfied while the constructional outlay may be very little and extra costs may be very low.

The heat pipe used according to one embodiment of the present invention is configured for utilizing evaporation heat of a medium, the condensed medium being adapted to be conducted within the heat pipe according to the wick principle.

The heat pipe may be configured for transferring the heat absorbed from the heating bar to the sealing bar along the sealing rail in a generally uniform manner so as to minimize differences in temperature of the heating bar when the heat is being transferred to the sealing bar and heating the sealing surface as uniformly as possible.

When the sealing rail is in operation, a maximum difference in temperature of less than 10° C., and preferably less than 6° C., may prevail on the sealing surface along the sealing rail.

According to an advantageous embodiment of the present invention, the heat pipe has a deformable outer wall so that, when the heat pipe is being mounted between the heating bar and the sealing bar, the outer wall will be able to adapt itself such that a respective comparatively large contact surface may be established between the heat pipe and the heating bar as well as the sealing bar. The resultant contact surface defined by the heating bar and the sealing bar may have an oval cross-sectional area. The oval cross-sectional area can ensure, during mounting, that a round cross-sectional area and cylindrical outer wall of the heat pipe may be deformed and partially brought into contact with the oval shape of the opening, thus leading to an increase in the contact surface, whereby good heat transfer from the heating bar to the heat pipe and from the heat pipe to the sealing bar will be possible.

The sealing rail may be configured as a two-part component by means of the heating bar and the separately formed sealing bar, preferably for the purpose of allowing an oval cross-sectional area or for facilitating introduction of the heat pipe into the sealing rail.

According to a preferred embodiment, the heating bar and the sealing bar are, with the exception of the contact surface for the heat pipe, connected to one another in a mutually heat-insulating manner, so as to achieve the highest possible efficiency of the heat pipe regarding compensation of differences in temperature.

The sealing bar may have a substantially T-shaped cross-sectional area so as to allow simple mounting.

In one embodiment of the present invention, the heat pipe has an outer diameter in the range of 6 to 20 mm, preferably 8 to 12 mm.

According to a preferred embodiment, the heat pipe is configured for a temperature range (operating range) of 60° C. to 200° C., preferably 80° C. to 150° C., so as to be particularly suitable for use in a sealing rail for sealing plastic bags.

The heat pipe may extend over the entire length of the sealing rail.

The heat pipe may be adapted to be inserted into an opening in the sealing rail.

According to a preferred embodiment, the heat pipe comprises two or more heat pipe portions so as to allow, especially in the case of long sealing rails, the use of advantageous standard lengths of heat pipes. According to the present invention, a sealing rail is a long sealing rail when it has a length of 500 mm or more, preferably 600 mm to 1000 mm.

A vacuum chamber machine according to one embodiment of the present invention comprises an above described sealing rail for evacuating and sealing medical products in a bag that is capable of meeting the stricter demands concerning the differences in temperature along the sealing rail required for use in the field of medicine.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawing, which forms a part of the specification and is to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views:

FIG. 1 is a perspective view of a vacuum chamber machine with a sealing rail according to one embodiment of the present invention;

FIG. 2 is a front sectional view of a sealing rail according to one embodiment of the present invention;

FIG. 3 is a front sectional view of a sealing rail according to an alternative embodiment of the present invention; and

FIG. 4 side sectional view of a heat pipe according to one embodiment of the present invention.

Like reference numerals always designate like components in the figures.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures.

The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.

FIG. 1 shows an open packaging machine in the form of a vacuum chamber machine 1 comprising a chamber lid 2, a frame 3, a chamber base 4 and a sealing rail 5 according to one embodiment of the present invention. For vacuum packaging a product 6, the latter may be placed into a plastic bag 7, and the plastic bag 7 may be placed onto the chamber base 4 in the vacuum chamber machine 1 so that the open area of the plastic bag 7 to be sealed rests on or is located above the sealing rail 5. When the chamber lid 2 has been closed in the direction of the arrow, the interior of the chamber thus formed can be evacuated and, subsequently, an upper sealing rail 8 that may be provided in the chamber lid 2 may press the plastic bag 7 against the sealing rail 5 during the sealing operation. The upper sealing rail 8 that may be provided in the chamber lid 2 may only be a counter pressure bar, but it may also be a heated sealing rail, or preferably a continuously heated sealing rail. The lower sealing rail 5 may be configured as a continuously heated sealing rail.

FIG. 2 shows a sectional view of the sealing rail 5 according to one embodiment of the present invention. The sealing rail 5 can be functionally divided into an upper area, sealing bar 10, and a lower area, heating bar 11. The sealing rail 5 may be configured as a one-part component or as a multi-part component. The one-part embodiment can be seen in more detail in FIG. 3 according to one embodiment of the present invention. The two-part embodiment, as shown in FIG. 2 exhibits a heating unit 12, which may consist of one or more heating elements, such as known tubular heaters, extending along the length of the sealing rail 5 so as to input heat along the entire heating bar 11, according to one embodiment of the present invention. The sealing bar 10 may have, on the upper side thereof, a sealing surface 13, which can be heated by means of the heating unit 12 to a sealing temperature suitable for the plastic bag 7. This temperature may be between 60 and 200° C.

The heating elements 12 may not exhibit a sufficiently homogeneous heat distribution so that excessive differences in temperature occur along the sealing rail 5 at the transition from the heating bar 11 to the sealing bar 10. In order to minimize these differences in temperature, the sealing bar 10 and the heating bar 11 may be thermally insulated in the lateral boundary areas 14. According to one embodiment of the present invention, they are connected to one another and mountable in a non-thermoconducting or an only slightly thermoconducting manner by means of known connection elements, which are not shown in detail. In the central area of this transition, an opening 15 may be formed that has a heat pipe 16 provided therein. When the sealing bar 10 is being mounted to the heating bar 11, the heat pipe 16 may get clamped, whereby the outer wall 17 of this heat pipe 16 may become deformed and brought, at least partially, into large-area contact with both the heating bar 11 and the sealing bar 10 so that good contact and good heat transfer can be accomplished.

In the following, the mode of operation and the influence of the heat pipe 16 will be described in more detail. In the case of the heat pipe 16, the heat may be absorbed by the heat pipe 16 along the length of the sealing rail 5 via the area of the outer wall 17 that is in contact with the heating bar 11. A medium 20 that works by making use of evaporation heat, the condensed medium 20 being conductable within the heat pipe according to the wick principle, may ensure within the heat pipe 16 heat compensation along the longitudinal orientation of the heat pipe 16. The heat pipe 16 may extend parallel to the sealing surface 13. This can have the effect that the area of the outer wall 17 that is in contact with the sealing bar 10 is heated with a more homogeneous distribution of heat. This may lead to a far-reaching compensation of differences in temperature on the sealing surface 13 in the longitudinal orientation.

FIG. 3 shows a variant of the sealing rail 5 where the sealing bar 10 and the heating bar 11 are, in common, configured as one part (e.g. as an aluminum rail), according to one embodiment of the present invention. Just as in the embodiment shown in FIG. 2, the heating unit 12 may be provided in the lower area of the heating bar 11. The opening 15′ may be provided in the sealing rail 5 in the form of an elongated mounting hole and, when the heat pipe 16 is being mounted, it may be introduced in the opening 15′ and, provided that the opening 15′ has adequately dimensioned tolerances with respect to the outer wall 17 of the heat pipe 16, a largely full-area contact can be established. In the case of this embodiment, heat transfer from the heating bar 11 to the sealing bar 10 may take place not only via the heat pipe 16 but also in the neighboring areas 14′.

Making reference to FIG. 4, the operating principle of the heat pipe 16 will now be explained. The heat pipe 16 may be provided with a cover 18 on its outer wall 17 and at both ends thereof, so that a hermetically sealed cylindrical body can be formed. In the interior, a capillary structure, such as a wick-like material 19 and a medium 20 that is evaporable and condensable, may be provided. The thermal energy W1 supplied in FIG. 4 from below can be produced by heating units 12, such as cartridges or tubular heaters. The different lateral distances between the arrows directed upwards onto the heat pipe 16 show that the thermal energy W1 introduced is distributed irregularly as regards the heat pipe 16. The thermal energy W1 leads to different physical states of the medium 20, which may be ammonia or in the simplest case also water, in the heat pipe 16. Depending on the respective temperature and kind of medium, these physical states may be different degrees of evaporation and condensation. By means of the wick-like material 19, a distribution V and, consequently, a compensation of thermal energy along the orientation of the heat pipe 16 can be accomplished, since, according to its respective state, the medium 20 can automatically spread within and along the wick-like material 19, thus causing a distribution of heat. This has the effect that on the upper, or opposite side of the heat pipe 16, a uniform distribution of the emitted thermal energy W2 may occur. The uniform distribution may be expressed by uniform distances between the arrows that are directed upwards and away from the heat pipe 16. This corresponds to a homogeneous distribution of heat along the upper side of the heat pipe 16. The pipe 16 may thus act as a homogenizer for the heat introduced in the sealing bar 10.

The present invention also comprises an advantageous embodiment in the case of which the heat pipe 16 is integrated into a sealing rail 5 according to FIG. 3 such that the outer wall 17 already defines part of the sealing rail 5 (i.e. the sealing bar 10 and the heating bar 11). The wick-like material 19 and the medium 20, as described in FIG. 4, may be directly integrated in the sealing rail 5.

According to the present invention, the sealing rail need not necessarily be configured as a straight bar. Also a closed circular shape is imaginable, so as to allow use in a sealing station of a tray sealer or a thermoform packaging machine for the purpose of producing air-tight circumferentially extending sealed seams. In this respect all shapes are imaginable.

From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting.

The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow. 

What is claimed is:
 1. A sealing rail for a packaging machine, the sealing rail comprising: at least one heating unit provided in a heating bar; a sealing surface provided on a sealing bar; and at least one heat pipe; wherein the at least one heat pipe is oriented parallel to the sealing surface and contacts the heating bar and the sealing bar so as to transfer heat homogeneously from the heating bar to the sealing bar.
 2. The sealing rail according to claim 1, wherein when the sealing rail is in operation, a maximum difference in temperature of less than 10° C. in a longitudinal orientation. prevails on the sealing surface.
 3. The sealing rail according claim 1, wherein the heat pipe has a deformable outer wall.
 4. The sealing rail according to claim 3, wherein the heat pipe is adapted to be mounted between the heating bar and the sealing bar, and wherein the outer wall is deformed during mounting of the heat pipe.
 5. The sealing rail according to claim 3, wherein a contact surface defined by the heating bar and the sealing bar has an oval cross-sectional area.
 6. The sealing rail according to claim 1, wherein the heating bar and the sealing bar are configured as separate components.
 7. The sealing rail according to claim 6, wherein the heating bar and the sealing bar are connected to one another in a mutually heat-insulating manner.
 8. The sealing rail according to claim 1, wherein the sealing bar has a substantially T-shaped cross-sectional area.
 9. The sealing rail according to claim 1, wherein the heat pipe is configured for a temperature range of 60° C. to 200° C.
 10. The sealing rail according to claim 1, wherein the heat pipe extends an entire length of the sealing rail.
 11. The sealing rail according to claim 1, wherein the heat pipe comprises two or more heat pipe portions.
 12. The sealing rail according to claim 1, wherein the sealing rail is incorporated with a vacuum chamber machine. 